In the semiconductor industry, it is known that growing a III-N material, such as GaN, on a silicon substrate is difficult, due in large part to the large crystal lattice mismatch (−16.9%) and the thermal mismatch (53%) between silicon and GaN. Thus, some type of buffer layer or layers is generally formed on the silicon substrate and the III-N material is grown on the buffer layer. Generally, the prior art buffer layers are either, complicated and expensive to form or do not adequately reduce the strain in the GaN due to crystal lattice mismatch.
In the prior art, various attempts are disclosed for the growth of different devices including III-V materials on silicon and other substrates. An article entitled “Growth of Atomically smooth AlN films with a 5:4 Coincidence Interface” by Shenk et al. in Materials Science and Engineering B59 (1999) 84-87, describes a SAW (Surface Acoustic Wave) device on Si(111) a substrate. An article entitled “Growth and Optical Properties of Gadolinium Aluminum Nitride Thin Films” by Chen et al. in Phys. Status Solidi C9, No. 3-4, 1040-1042 (2012), describes the growth of GdxAl1-xN on silicon substrate (100) for the enhanced emission of UV luminescence at about 310 nm. In a U.S. Pub. 2010/0308375 entitled “Rare Earth Enhanced High Electron Mobility Transistor and Method for Fabricating Same”, Birkham describes a device including an optional buffer of GaN, AlN, or ZnO. The buffer can be eliminated if the substrate is a “suitable native substrate” which III-V material can be grown directly on (no examples given). An insulator layer of intrinsic GaN deposited on the buffer is doped with a rare earth to improve the insulating qualities. An article entitled “Visible Cathodoluminescence of Er-doped Amorphous AlN Thin Films” by Guruvmurugan et al. in Appl. Phys. Lett. 74, 3008 (1999) describes the cathodoluminescence of erdium doped amorphous AlN. In all of these articles and publications the rare earth does not appear to be included for any deposition enhancement but for the optical qualities. Plus in the Guruvmurugan et al. article the material is amorphous so that no crystal matching is possible or required.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.
Accordingly, it is an object of the present invention to provide new and improved methods for the growth of single crystal III-N material on a silicon substrate.
It is another object of the present invention to provide new and improved methods for the growth of single crystal III-N material on a silicon substrate with reduced dislocation density and relatively simple to perform.
It is another object of the present invention to provide new and improved substantially stress free, single crystal III-N layers grown on a silicon substrate.